Marcos A. Vasquez and his friends were in Cancun, Mexico, over the weekend when five people were killed at a crowded beachfront nightclub.

Vasquez and his friends tried getting tickets to attend the BPM electronic music festival, but weren’t able to.

Moments after screaming concertgoers at the international festival stormed out of the nightclub, Vasquez and his friends witnessed the chaos from a place next door to where the event was happening.

Vasquez spoke to KFOX14 and CBS4 during a phone interview Monday afternoon. He said he had witnessed a shooting before but nothing of this magnitude.

"This event was for about 80,000 persons I think. So there was a lot of people on the street running," Vasquez said.

"We were very, very terrified because we didn't know what was happening," Vasquez said.

Quintana Roo state Attorney General Miguel Angel Pech ruled out any terror attack, but said the shooting erupted when festival security personnel tried to stop a man from entering the Blue Parrot club with a gun.

Three of those killed were part of the security detail at the 10-day BPM electronic music festival, Pech said. State officials said the dead included two Canadians, an Italian and a Colombian. The gunman apparently fled.

“We thought it was a terrorist attack because the first stampede of people was massive,” said Vasquez in his Facebook post.

Video Vasquez captured shows concertgoers running out and patrons at the place he was in ducking for cover. A woman screaming in Spanish is heard “someone is lying on the ground dead!” and a man frantically saying in Spanish “crawl into the bathroom now.”

The shots set off a rush for the exits that accounted for at least some of the injuries. The lone female victim was apparently killed during the stampede. Rescue workers tended to bloodied survivors, and Pech said 15 people were injured, included one Mexican woman who was seriously injured.

Pech said eight of the injured — including two U.S. citizens — had been treated for less-serious injuries at local hospitals and released. Canada's Global Affairs Office confirmed at least one Canadian died, said it was investigating the other reported fatality, and said at least two Canadians were injured.

Italy's Foreign Ministry confirmed one its citizens died.

The El Pasoan said he, his girlfriend and the people around him locked themselves inside a small bathroom.

"I started to record. I figured something was happening but I didn't know what until I saw this guy on the floor and he had a gunshot wound," Vasquez said.

Vasquez described the room as small for the eight of them panicking about what was going on outside.

"We were just waiting for I don't know, someone to shoot or kill us. We were expecting the worse," Vasquez said.

He said when they went out, they witnessed injured people asking for help.

"He had a bullet wound on his arm," Vasquez said.

The attorney general said a lone gunman apparently tried to enter the nightclub about 2:30 a.m., but was denied access because he had a gun.

The gunman began to exchange fire with another person inside, he said, and festival security personnel who tried to stop the shooting came under fire. He said 20 bullet casings from three different pistols had been found at the scene, and said it was unclear if the security detail had been armed or fired any of the weapons.

Pech said the gunman himself apparently escaped, though three people were detained nearby. It was not known if they had been involved in the shooting.

The government of the township that includes Playa de Carmen referred in a statement to "attackers who fired shots," but did not provide further details.

Rodolfo Del Angel, director of police in Quintana Roo, told the Milenio TV station that the shooting was the result of "a disagreement between people inside" the nightclub and said security guards had come under fire when they tried to contain the dispute.

"When we got out, we got into a taxi and I told the taxi driver, 'just get me out of here,'" Vasquez said.

Vasquez said he woke up Monday morning feeling happy to be alive.

"It is nice to say 'this happened yesterday and we are still here,'" Vasquez said. He said he can't wait to be home in El Paso but also feels terrible for the lives that were lost.

"We feel sorry for the people who were killed. This is the first time that something happens in a tourist zone here in Playa del Carmen. It started as a discussion. The people who were killed weren't targets. This is not our Mexico. I hope that people will forget this," Vasquez said.